I don't understand how that would work at all...
The SendFile function has not access to OUT. (OUT is on the client program which is on an entirely different computer than then the server)
Regardless, I tried that and it does not seem to work, are you sure that the book did not mean to send a "close OUT" variable after the file?
Although thanks for the input, the concept of not being sure whether they had finished writing back and forth was what I had suspected. I just want to get a concrete verification